There are two parallel ridges bordering the plain on which Gettysburg stands. The long Seminary Ridge, stretching from north to south about a mile west of the town, gets its name from the Lutheran Theological Seminary standing upon it; and the Cemetery Ridge to the south of the town, which partly stretches up its slopes, has on its northern flat-topped hill the village cemetery, wherein the principal grave then was that of James Gettys, after whom the place was named. There is an outlying eminence called Culp's Hill farther to the east, making, with the Cemetery Ridge, a formation bent around much like a fish-hook, with the graveyard at the bend and Culp's Hill at the barb, while far down at the southern end of the long straight shank, as the ridge extends for two miles away, with an intervening rocky gorge called the Devil's Den, there are two peaks, formed of tree-covered crags, known as the Little Round Top and the Big Round Top. These long parallel ridges, with the intervale and the country immediately around them, are the battlefield, which the topographical configuration well displays. It covers about twenty-five square miles, and lies mainly southwest of the town. It was on June 28th that General Meade unexpectedly assumed command of the Union army, and he was then near the Potomac. General Ewell with the Confederate advance guard had gone up the Cumberland Valley as far as Carlisle, and his troopers were threatening Harrisburg. Nobody had opposed them, and the Confederate main body, which had got much ahead of Hooker, was at Chambersburg. Lee being far from his base, and hearing of the Union pursuit, then determined to face about and cripple his pursuers, fixing upon Gettysburg as the point of concentration. He ordered Ewell to march south from Carlisle, and the other commanders east from Chambersburg through the mountain passes. The Union cavalry advance under General Buford reached Gettysburg on June 30th, ahead of the Confederates, and Meade's army was then stretched over the ground for more than forty miles back to the Potomac, all coming forward by forced marches. As soon as Meade became aware of Lee's changed tactics he concluded that this extended formation was too risky, and decided to concentrate in a strong position upon the Pipe Creek hills in Maryland, about fifteen miles south of Gettysburg, and issued the necessary orders. Thus the battle opened, with each army executing a movement for concentration. THE GREAT BATTLE.